The invention relates to the automatic welding of bevelled tubes, inter alia pipes or lines or the like adapted to be placed under water.
All known automatic welding apparatus are designed to have regard to many factors concerned in achieving a good-quality weld in the first two welding runs. The first two welding runs are vital because they determine a satisfactory joining of the tubes in the clamped part by the bevels of the tubes, such part subsequently serving as a support for consecutive weld layers produced by the filling runs.
It is known to use special bevels to facilitate automatic welding by some apparatus. Unfortunately, the special bevels are either expensive to contrive, since they must be made to close dimensional tolerances and have more than two changes of inclination, or relatively inexpensive but with the disadvantage of requiring the tubes to be at a carefully predetermined distance apart from one another. There are even bevels whereby the tubes can be presented to one another without spacing, a heel being provided at the base of the assembly, but the heel is limited underneath by reverse bevels and above by bevels at approximately 45.degree. followed by flanks at an inclination of approximately 5.degree. to the axis of the groove bounded by the bevels.